V4L/DVB (11660): zoran: fix bug when enumerating format -1

If someone requests a format at fmt->index == (unsigned)-1 and the first
format in the array doesn't have the requested type then num will still be
-1 when it's compared to fmt->index and there will appear to be a match.

Restructure the loop so this can't happen.  It's simpler this way too.  The
unnecessary check for (unsigned)fmt->index < 0 found by Roel Kluin
<roel.kluin@gmail.com> is removed this way too.
Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/zoran/zoran_driver.c

@@ -1863,22 +1863,20 @@ static int zoran_querycap(struct file *file, void *__fh, struct v4l2_capability
 
 static int zoran_enum_fmt(struct zoran *zr, struct v4l2_fmtdesc *fmt, int flag)
 {
-	int num = -1, i;
+	unsigned int num, i;
 
-	for (i = 0; i < NUM_FORMATS; i++) {
-		if (zoran_formats[i].flags & flag)
-			num++;
-		if (num == fmt->index)
-			break;
-	}
-	if (fmt->index < 0 /* late, but not too late */  || i == NUM_FORMATS)
-		return -EINVAL;
-
-	strncpy(fmt->description, zoran_formats[i].name, sizeof(fmt->description)-1);
+	for (num = i = 0; i < NUM_FORMATS; i++) {
+		if (zoran_formats[i].flags & flag && num++ == fmt->index) {
+			strncpy(fmt->description, zoran_formats[i].name,
+				sizeof(fmt->description) - 1);
+			/* fmt struct pre-zeroed, so adding '\0' not neeed */
 			fmt->pixelformat = zoran_formats[i].fourcc;
 			if (zoran_formats[i].flags & ZORAN_FORMAT_COMPRESSED)
 				fmt->flags |= V4L2_FMT_FLAG_COMPRESSED;
 			return 0;
+		}
+	}
+	return -EINVAL;
 }
 
 static int zoran_enum_fmt_vid_cap(struct file *file, void *__fh,